you could convery you normal map to a grayscale image and possibly overlay it on the texture to get some of the areas to darken etc. Better way to do this would be to export a displacement I would expect though.

hi hunnybee,
the main problem with using normal maps as a template for painting is that they are intended to represent geometry rather than light information. a better option for a template would be to bake an ambient occlusion map, then take this into photoshop to use it as a template for painting. good luck